Source
chown www-data:www-data -R * # Let Apache be owner
find . -type d -exec chmod 755 {} \; # Change directory permissions rwxr-xr-x

The above command will say you days

Finds all the directories and sets them as:

read,write,exec by user

read,exec by group and anon

find . -type f -exec chmod 644 {} \; # Change file permissions rw-r–r–

above command finds all the files and sets them to:

read,write by user

read only by group and anon